received an email telling him when to restart his phone to be on the new plan. We were already with AT&T, we didn't have to do anything with our phones, it was all done on their end.

I think it's easier if you have an eSim rather than an actual Sim card, but I'm not sure about that. It was not difficult at all, and ONLY ONE person has to have a BYU Net ID, you can add friends and neighbors to your heart's content, they encourage it.